Hi Feilpe,
Which GHC version do you use?
With 7.6.3 I have all the same BUT Optimal'/10 260 ns. It's better than 1200 ns
but still bad. Also there are INLINEs everywhere at vector-algorithms.
Seems to be compiler problem.
21.08.2014, 18:32, "Felipe Lessa"
On 21-08-2014 11:22, Felipe Lessa wrote:
I suggest that you add a few SPECIALIZE pragmas to vector-algorithms and check its performance again.
Scratch that, I remembered that one may just copy & paste :).
Here's the code and criterion results: https://gist.github.com/meteficha/1acef6dc1e1ed81b63ae
This is the relevant part:
benchmarking --nothing--/10 time 151.5 ns (151.2 ns .. 151.8 ns) 1.000 R² (1.000 R² .. 1.000 R²) mean 151.8 ns (151.6 ns .. 152.1 ns) std dev 868.8 ps (732.4 ps .. 1.030 ns)
benchmarking --best--/10 time 157.4 ns (157.1 ns .. 157.7 ns) 1.000 R² (1.000 R² .. 1.000 R²) mean 157.1 ns (156.6 ns .. 157.4 ns) std dev 1.297 ns (786.7 ps .. 2.366 ns)
benchmarking Optimal/10 time 1.173 μs (1.168 μs .. 1.180 μs) 1.000 R² (1.000 R² .. 1.000 R²) mean 1.194 μs (1.187 μs .. 1.204 μs) std dev 27.45 ns (22.18 ns .. 36.34 ns) variance introduced by outliers: 29% (moderately inflated)
benchmarking Optimal'/10 time 157.7 ns (157.5 ns .. 158.0 ns) 1.000 R² (1.000 R² .. 1.000 R²) mean 157.8 ns (157.5 ns .. 158.2 ns) std dev 1.178 ns (872.4 ps .. 1.965 ns)
Optimal', which is a copy of Optimal, takes almost the same as --best--, which does no comparisons at all!
So vector-algorithms really needs either to force INLINE (leading to code size bloat) or sprinkle SPECIALIZE pragmas everywhere. I suggest contacting the package's maintainer to see what their thoughts are on this matter.
Cheers,
-- Felipe.